This invention relates to the removal of oil products floating on water in general and more particularly to an improved method and apparatus for removing such oil using a sponge like material without removing that material from the water.
Various methods and apparatus have been developed for removing oil products floating on water. One type of these utilizes a sponge or mop which is basically oleophilic and hydrophobic. That is to say, it is a sponge which will attract oil but will not attract water. In such devices an endless belt of such material is typically formed and the endless belt moved through the water and the material containing oil removed from the belt as it is brought aboard a ship, boat or the like. Typical of such apparatus is that disclosed in U.S. Pat. No. 3,700,593 in which a porous body with an average porousity of at least 80% and comprising an organic polymer having a density between 0.85 and 1.50 such as polypropylene or polyomides is used as the sponge material. A belt of this material is rotated between two vessel or a land station and a vessel with means for squeezing the oil out of the material located on board the collecting vessel. Another similar apparatus is disclosed in U.S. Pat. No. 3,617,552. In the apparatus disclosed therein a belt moves in and out of the water, with a roller for the belt provided under water. The disclosed belt is multilayer belt with different pore sizes with a suitable material being indicated as polyurethane. Another apparatus is disclosed in U.S. Pat. No. 3,744,638. Here the endless belt runs between a vessel containing means for driving the belt and means for squeezing the oil therefrom and a buoy having a rotating drum thereon. The disclosed belt material is a polypropylene fiber. A manner of making a particularly desireable type of belt from propylene material is disclosed therein.
Another device is disclosed in U.S. Pat. No. 3,772,161 in which a plurality of chambers hold regenerable porous filler material, preferably reticulated hydrophobic foam such as polyurethane. Once again, two separate pore sizes of the foam are used. The arrangement of this apparatus is essentially the same as that in U.S. Pat. No. 3,617,552. Finally, in U.S. Pat. No. 3,679,058 an oil absorbent boom comprising porous hydrophobic foam material such as reticulated polyurethane foam and means for squeezing the oil therefrom is disclosed.
As is evidenced by the number of prior art patents relating to this subject there is a great need for apparatus of this type. The activity in this area is undoubtably due to increased concern for the environment and recent legislation association therewith. That the types of materials described in these patents work well in absorbing oil spills, is evident. However, in each of these prior methods and apparatus there is one serious deficiency. The material must be brought up out of the water laden with oil and conveyed to a squeezing area. In order to do so, it is necessary that expensive means be provided to insure that the belt or sponge has sufficient structural strength to withstand the stresses placed upon it. Even by taking these steps such belts are subject to breakage requiring replacement and at least a temporary cessation of operations. Such is clearly not desireable since oil spills can quickly spread and cause serious damage to beaches and to the ocean where oil pollution is particularly damaging.
In another attempt to solve this problem in the prior art, a plurality of relatively small sponges, i.e. of about the the size of a fist, were shot into the water and then picked up, and the oil squeezed therefrom. Afterwards, they were again placed in the water. Size obviously was kept small because even a small sponge full of oil becomes extremely heavy. Thus, to pick a large sponge out of the water entails great difficulty.
More significantly, these prior art devices are not capable of picking up extremely large oil spills. Oil spills of 30 to 85 thousand tons have occurred recently and with the advent of large supertankers spills even in excess of this amount can possibly occur. In such a case, a particularly large absorbent belt which would have to extend for 5 miles or more and which can be used in the open seas or a plurality of larges sponges would be necessary. It is quite evident that belts and sponges of these dimensions can not be handled by presently existing apparatus.
In view of this, the need for an improved method and apparatus for removing oil products floating on water, i.e., for picking up oils spills, becomes evident.